1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus and a semiconductor device manufacturing method, more particularly a semiconductor manufacturing apparatus emitting light having a high brightness, high energy, and short pulse width for ablation to form a pattern on a wafer and a semiconductor device manufacturing method using the apparatus.
2. Description of the Related Art
In a conventional process of production of a semiconductor device, when patterning a wafer or a coating film formed on it, it is usually etched using a resist as a mask. For the above etching, first, the resist is coated on the surface of the material to be etched. Next, this is exposed using a photolithographic mask to transfer the pattern formed by the photolithographic mask on the surface of the resist (photolithography process). Next, an unnecessary part of the resist is removed by using a developing fluid. By the development, an exposed or unexposed part of the resist is removed. After this, the material to be etched is etched using the patterned resist as a mask.
Since formation of a pattern by etching requires the above series of steps, there is a disadvantage of the required time becoming long. Also, development of the resist or etching of various materials requires different and expensive apparatuses. Further, in the case of dry etching, a large amount of etching gas is necessary. This has become one of the reasons for raising the production costs of semiconductor devices. There is also a problem in that the environmental load of the etching gas used for the etching is large.
Unlike the above etching, the method is also known emitting light using a high-brightness light source and sublimating the material to form a pattern (ablation). In ablation, the inner-shell electrons of various materials participate in a photochemical reaction to form a pattern to a high precision.
As materials for which it is confirmed a pattern can be formed by ablation, specifically the organic material polymethyl methacrylate (R. Srinivasan and Bodil Braren, Applied Physics Letters, 1988, 53, 1233) and Teflon (S. Kuper and M. Stuke, Applied Physics Letters, 1989, 54, 4), the inorganic material SiO2, and the semiconductor material GaAs can be mentioned.
Also, there is an example of not forming a resist on the wafer but directly emitting laser light passing through a mask on the surface of the wafer to form a pattern by ablation (Sugioka, Koji, Tashiro, Hideo, and Wada, Tomoyuki, OPTRONICS, 1998, 98).
Further, a processing device using ablation to be able to form a pattern on, for example, a polyimide film is disclosed by Japanese Unexamined Patent Publication (Kokai) No. 8-155667. This processing device emits a laser beam having a pulse width of about 20 ns, for example, to process a material.
Alternatively, a method and apparatus using ablation to form a signal groove (pit) on an optical disk comprised of a synthetic resin are disclosed in Japanese Unexamined Patent Publication (Kokai) No. 8-124226. According to this method of production of an optical disk, it is possible to use a fourth harmonic (266 nm wavelength) of for, example, an Nd:YAG laser to form a pit (currently 0.4 xcexcm in width).
In addition to the above, a method of production of a liquid-crystal display element using ablation to form a pattern on thin film layers of liquid-crystal display elements is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 8-6070. In this method of production, a pattern is formed by using an excimer laser of an ultraviolet region such as a KrF laser (248 nm wavelength), a XeCl excimer laser (308 nm wavelength), or an ArF excimer laser (193 nm wavelength). Also, the pulse width of these lasers is about 10 to 100 ns.
However, according to the above conventional examples of forming patterns by ablation, although high precision processing is possible compared with etching, it has been difficult to form a pattern sufficiently fine to meet with the increasing miniaturization of semiconductor devices. In the conventional ablation method, a pattern is formed by using a nanosecond pulse. Therefore, the density of photons per unit time becomes lower than even that in the case of using an ultra-short time pulse shorter than that such as a picosecond or femtosecond order pulse.
When performing ablation under conditions of low photon density, it is necessary to make the molecules of the material change to a first excited state, then change to a second and higher excited states by simultaneously emitting light of two different wavelengths. Therefore, there is the restriction that it is necessary to make the imaging positions of the high-brightness light sources of the two wavelengths match and secure the paths for the lights of the two wavelengths and the hardware becomes complicated.
There are many unclear points regarding the mechanism by which ablation occurs. In the actual process of production of semiconductors, the parameters for controlling the ablation process, the suitable system configurations, etc. have not yet been established.
An object of the present invention is to provide a semiconductor manufacturing apparatus and a method of producing a semiconductor device able to form a sufficiently precise pattern by ablation.
To achieve the above object, the semiconductor manufacturing apparatus of the present invention is a semiconductor manufacturing apparatus comprising a light source for emitting light of a first wavelength on a surface of a wafer and a mask through which at least part of the light of the first wavelength passes and removing a material of the part of the wafer exposed by the light of the first wavelength by vaporization, characterized in that the light source comprises an electron beam generating means for generating an electron beam and a light emitting means for emitting light of a second wavelength longer than the first wavelength and in that the light of the first wavelength is an inverse Compton scattered light obtained by collision of electrons in the electron beam with photons in the light of the second wavelength causing the energy of the electrons to be given to the photons.
The semiconductor manufacturing apparatus of the present invention preferably is characterized in that the light emitting means comprises a laser. The semiconductor manufacturing apparatus of the present invention more preferably is characterized in that the laser comprises a pulsed laser.
The semiconductor manufacturing apparatus of the present invention preferably is characterized in that the light source has at least a pair of reflecting means for reflecting the light of the second wavelength back and forth.
Also, to achieve the above object, the semiconductor manufacturing apparatus of the present invention is a semiconductor manufacturing apparatus comprising a light source for emitting a pulsed light to a surface of a wafer and a mask through which at least a part of the pulsed light passes and removing a material of the part of the wafer exposed by the pulsed light by vaporization, characterized in that the pulsed light emitted from the light source has a wavelength of not more than about 300 nm and a pulse width of not more than about 1 ns.
The semiconductor manufacturing apparatus of the present invention preferably is characterized in that the light source comprises a light source emitting a synchrotron radiation light. Alternatively, the semiconductor manufacturing apparatus of the present invention preferably is characterized in that the light source emits a laser plasma light.
Due to this, it is made possible to make inner-shell electrons of a material at the surface of a wafer dissociate and make the material of the light exposed part subliminate. According to the semiconductor manufacturing apparatus of the present invention, since a light source for emitting light of a high brightness, high energy, and short pulse width is used, it is possible to form a distinct fine pattern on the surface of a wafer.
Further, to achieve the above object, the semiconductor device manufacturing method of the present invention is characterized by comprising the steps of generating light of a first wavelength; emitting the light of the first wavelength to the surface of a wafer via a mask through which at least part of the light of the first wavelength passes; and removing material of a part of a wafer exposed by the light of the first wavelength by vaporization, wherein the step of generating the light of the first wavelength comprises the steps of generating an electron beam from an electron beam generating mean; generating light of a second wavelength longer than the first wavelength; and making electrons in the electron beam collide with photons in the light of the second wavelength to generate inverse Compton scattered light with the energy of the electrons given to the photons.
The semiconductor device manufacturing method of the present invention preferably is characterized in that the light of the second wavelength comprises a laser light. The semiconductor device manufacturing method of the present invention more preferably is characterized in that the laser light comprises a pulsed light.
The semiconductor device manufacturing method of the present invention preferably is characterized in that the step of generating the light of the first wavelength comprises a step of using at least a pair of reflecting means to reflect the light of the second wavelength back and forth to make the electrons collide with the photons.
The semiconductor device manufacturing method of the present invention preferably is characterized in that a dielectric layer is formed on the surface of the wafer. Alternatively, the semiconductor device manufacturing method of the present invention preferably is characterized in that a semiconductor layer is formed on the surface of the wafer. Alternatively, the semiconductor device manufacturing method of the present invention preferably is characterized in that a metal layer is formed on the surface of the wafer.
To achieve the above object, the semiconductor device manufacturing method of the present invention is characterized by comprising the steps of emitting a pulsed light of predetermined wavelength to a surface of a wafer via a mask through which at least a part of the pulsed light passes and removing a material of the part of the wafer exposed by the pulsed light by vaporization, wherein the pulsed light has a wavelength of not more than about 300 nm and a pulse width of not more than about 1 ns.
The semiconductor device manufacturing method of the present invention preferably is characterized in that the pulsed light is a synchrotron radiation light. Alternatively, the semiconductor device manufacturing method of the present invention preferably is characterized in that the pulsed light comprises a laser plasma light.
Due to this, it is made possible to perform ablation of a material at the surface of a wafer and to form a fine pattern distinctly. According to the semiconductor device manufacturing method of the present invention, unlike the case of conventional etching, a series of steps such as exposure and development of a resist and etching using the resist as a mask becomes unnecessary. By emitting a light of high brightness, high energy, and short pulse width on the surface of a wafer via a mask, the material of the light-exposed part can be removed, so it is made possible to simplify the process of production.
Also, in the semiconductor device manufacturing method of the present invention, when forming a resist on the surface of the wafer and emitting light there, it is also possible to continuously pattern the resist and pattern a base wafer material.